When a subsea well for extracting petroleum, for example, is established, a well-foundation system is installed on the seabed. A conventional base is usually established by a hole being drilled in the seabed (usually 36″ or 42″), in which a conductor casing (usually 30″ or 36″) is lowered into and fixed in the unconsolidated masses by a cement slurry being pumped in for the purpose of completely filling the space between the conductor casing and the hole wall. Thereby it is sought to achieve two primary aims:
1) the cured cement is to give full lateral support to the conductor casing up to the seabed, and
2) the cured cement is to give enough cover and strength for the first coupling of the conductor casing to be fully embedded and protected from any movements transmitted from a connected riser system to the conductor casing.
It turns out in practice that loss of cement slurry into, above all, permeable layers of unconsolidated mass may occur, and the conductor casing may move during the curing of the cement. This leads to the cement having a reduced quality, and it leads to the stiffness of the conductor casing being reduced to such a degree that specific design requirements are not reached, with the consequence that the fatigue strength of the well will be too low or that the load capacity of the well will not be fulfilled.